1. Field of the Invention
The present invention relates to a device for controlling the rotation of a reel of filamentary material.
2. Description of the Prior Art
In the processing of wire, or other filamentary material, the wire supply usually is coiled on a reel which is mounted on a wire feeding apparatus, such as a turntable that can rotate to allow the wire to be delivered to the wire processing machine.
Free-running turntables have been used as rotatable mounts for the reels. However, free-running turntables have limitations and disadvantages which have been magnified by a trend to multi-reel processing machines and larger weight coils for increased productivity.
At start-up when a free-running turntable is employed, a sufficient pull must be applied on the wire to be uncoiled in order to overcome the starting torque of the turntable and to establish a constant momentum of the reel. An intolerable load may be imposed on the processing devices, causing damage to equipment and/or loss of material and production time.
Tangling may also be encountered at start-up, especially when heavy coils are employed. A tangle may occur in the reel as the first few outgoing laps of wire are drawn tightly within the coil. The result of the tangle may be malfunction or damage to the processing equipment, or alternatively, the coil may be pulled off the turntable.
Further problems may be encountered during the shut-down of the system when the turntable continues to rotate freely, thus causing the outer laps of wire to loosen and drop about the base of the turntable. Some of the laps of wire must then be gathered and rewound, and the turntable must be prepared for a restart.
In view of the above difficulties associated with free-running turntables, it has been recognized that there is a need for a mechanism whereby the rotation of a reel can be controlled to adjust the tension of the out-going material. Numerous devices have been developed in an attempt to improve the free-running turntable.
For example, U.S. Pat. No. 2,923,493, issued Feb. 2, 1960 to Fitzgerald et al, discloses a device wherein the rotation of the reel is normally free-turning, but the tension in the out-going material can be controlled by the application of a manually adjustable braking mechanism which is forcibly applied by means of pressurized air. The device has an auxiliary feature comprising an air cylinder having a vertically reciprocatable piston rod to engage and disengage the device from the reel.
U.S. Pat. No. 3,081,957, issued Mar. 19, 1963 to Van de Bilt, describes a wire-feeding apparatus wherein a reel having a horizontally mounted axis of rotation can be driven by a pneumatic cylinder which engages the reel via a free-wheel transmission, and a spring-forced brake can be released by a second pneumatic cylinder, both cylinders being actuated by a valve or slide which is adjusted by a device responding to the pull exerted on the outgoing wire. Here the driving and braking forces are applied by two distinctly different and independently operated mechanisms.
U.S. Pat. No. 3,137,452, issued June 16, 1964 to Winders, discloses a mechanism whereby the rotation of a reel is powered by an electric motor operating at constant speed and engaged through a chain, belt or cable to a variable speed pulley connected on a drive shaft in the unit. Braking is achieved through a mechanism, separate from the drive unit as in the Van de Bilt apparatus, incorporating a shoe and drum arrangement actuated by means of a pressurized fluid cylinder.
It is an object of the present invention to provide an improved apparatus for the feeding of filamentary material, for example wire, from a reel wherein the rotation of the reel may be controlled throughout start-up, production and shut-down.